The present invention relates to an adjuster releasing apparatus for a drum brake.
A conventional adjuster releasing apparatus of a manual type for use in a drum brake is disclosed, for example, in an Examined Japanese Utility Model Publication No. Hei. 2-47779. In the conventional apparatus of this type, a second operation opening portion passing from a backing plate side to an adjuster lever side is formed on a web of brake shoes. In such a configuration, a first driver is inserted from a first operation opening portion of the backing plate and a second driver is inserted from the first and second operation opening portions, so that an adjuster gear is rotated by the first driver whereas the adjuster lever is pushed by the second driver thereby to disengage from the adjuster gear. As a result, the adjuster gear and an adjuster screw rotate relatively to each other so that the adjuster screw axially moves and the brake shoes engaging with the adjuster screw are radially expanded or contracted to thereby adjust a shoe gap.
In such a conventional adjuster releasing apparatus installed in a drum brake, however, there is a possibility that the adjuster lever is plastically deformed so that in its normal function is damaged by strong pushing force when the adjuster lever is pushed up by the second driver. Accordingly, the adjuster lever is subjected to flange-working or carburizing quenching to improve the rigidity thereof. There would however raise another technical problem in that not only the work is troublesome but defective products are apt to be generated because of large deformation due to quenching.